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Re: Tyrannosaur numbers
It seems to me that there may be a slight positive
preservational bias re tyrannosaurs. The old water
hole was a logical place for that final fall for
several reasons, and a good place to get fossilized.
--- Phil Bigelow <firstname.lastname@example.org> wrote:
> John Horner has an informed opinion on the number of
> _T. rexs_ that
> existed at any one time, and from my limited
> experience as an interested
> amateur, I think I'll agree with him. _T. rex_
> appears to be quite
> common in the Hell Creek Formation.
> For a number of years, paleontologists believed that
> _T. rex_ was a rare,
> or at least was an uncommon, taxon. But the reason
> for that belief is
> simple. After Barnum Brown and Harley Garbani
> retired, people just
> stopped searching for _T. rex_ skeletons. Things
> started to change
> around 1988 after Kathy Wankel stumbled upon
> MOR-555. Since then,
> Horner's team has dug up a number of partial
> skeletons in Montana, and
> Stan Sacrison and the Larson Bros. have done the
> same in South Dakota.
> Another _T. rex_ skeleton was found in Sask. Canada.
> And in Alberta,
> Canada, Phil Curie has dug up a few new skeletons
> and reopened old _T.
> rex_ quarries. Then there is the beautifully
> preserved South Dakotan
> "Z-rex" and a number of other amateur finds. All
> are post-Wankel
> FWIW, shed _T.rex_ teeth (representing a variety of
> growth stages) are
> common fossil finds. In some facies (rock layers),
> juvie(?) _T. rex_
> teeth are the dominant theropod taxon.
> As far as predator/prey ratios go, this only means
> that there must have
> been *way more* prey species wandering around the
> late Maastrictian North
> American landscape than we now believe.
> If you have access to the scientific literature, get
> a photocopy of the
> following paper:
> White, P.D., D.E. Fastovsky, and P.M. Sheehan. 1998.
> Taphonomy and
> suggested structure of the dinosaurian assemblage of
> the Hell Creek
> Formation (Maastrichtian), eastern Montana and
> western North Dakota.
> _Palaios_, volume 13:41-51.
> White et. al estimate that _T. rex_ constituted 4%
> of the entire Hell
> Creek dino population. That is a significant
> percentage, and it is equal
> to the Hell Creek dromaeosaurid, troodontid and
> population percentages, *combined*.
> <pb> (who's been posting WAY to much recently. It
> must be the increased
> light levels of the season.)
> On Tue, 24 May 2005 10:54:39 +1000 Benjamin Hughes
> > Hi all
> > I'm relatively new to the DML, certainly no expert
> like manyof you
> > here, but
> > jut thought I'd add my bit. I have ideas and if
> I'm wrong then I'm
> > happy to
> > hear why.
> > I have heard (coan't remember source, sorry) that
> there are very few
> > Tyrannosaur fossils ever found. Whether this means
> that few have
> > been found
> > out of a large amount still undiscovered, that few
> of the animals
> > ever
> > happened to be fossilised in the first place, or
> that there were few
> > Tyrannosaurs ever in existance at all, I am not
> > My point is that if it were true that there were
> few Tyrannosaurs,
> > then this
> > would most likely mean that it was simply because
> they were
> > innefective
> > predators, too big and cumbersome to catch faster
> prey, or to
> > compete with
> > slightly smaller predators.
> > Is there any way of knowing without the actual
> fossils the number of
> > Tyrannosaurs that existed?
> > ~Ben
> > -~
> > The Australian Discworld Convention -